A health care professional wants to determine whether individuals with hypertension who take Atenolol have significantly lower systolic blood pressure than individuals with hypertension who do not take Atenolol. For individuals who have not been prescribed Atenolol, the population systolic blood pressure mean is 165 ( = 165).The sample of30 individuals who take Atenolol have an average (mean) systolic blood pressure of 147, with a sample standard deviation of 6.On the basis of these data, can the researcher conclude that the Atenolol significantly lowers systolic blood pressure?

The appropriate statistical procedure for this example would be a: